Field
The field of the invention relates to an apparatus and method for an inductor coil, and, more particularly an apparatus and method for toroidal induction, wherein the specific configuration and other characteristics of the frame and coil geometry contribute to increased electro-magnetism and inductance.
Related Art
Inductors are unresisting electronic components that store energy in the form of a magnetic field. Every individual conductor has a certain amount of inductance associated with it. In order to obtain higher values of inductance, the wire can be formed into a loop or coil. The amount of inductance attributable to a particular inductor device is generally proportional to the number of turns in the coil, the radius of the coil and the type of material around which the coil is wound.
For a particular inductor having a precise number of turns and a precise coil radius it is well known that an air core will result in the least inductance because it has a permeability of 1.0 (the terms permeability and permittivity as used herein should be understood to mean relative permeability and relative permittivity, respectively). Other types of dielectric core materials will behave similarly if they also have a relative permeability close to 1.0. Conversely, ferromagnetic materials, which have higher permeability values, are often used as core materials to increase the inductance achieved for a particular coil configuration. Iron powder or ferrite cores do not need the additional air gap since it is integrated into the material and, in consequence, spread within the complete core volume. This reduces the eddy current losses in the winding and the remaining eddy current losses are distributed throughout the winding length.
The main advantage of the toroidal shape lies in its symmetry where, the amount of magnetic flux that escapes outside the core (leakage flux) is low, therefore it is more efficient and thus, radiates less electromagnetic interference (EMI) which must be reduced to the levels defined by international standards to ensure that one equipment is able to work with other equipment. Because the toroid is a closed-loop core it will have a higher magnetic field and thus higher inductance and Q factor than an inductor of the same value with a straight core (solenoid coils). This is because most of the magnetic field is contained within the core. By comparison, with an inductor with a straight core, the magnetic field emerging from one end of the core have a long path through air to enter the other end. In addition, because the windings are relatively short a toroidal transformer will have a lower secondary impedance which will increase efficiency and electrical performance.
Toroid inductors are used in medical devices, telecommunications, musical instruments, industrial controls, refrigeration equipment, ballasts, electronic clutches, electronic brakes, in the aerospace & nuclear fields, in air conditioner equipment and in amplifiers. Other applications include noise filtering for switching regulators, power supplies, power amplifiers and train control circuits.
U.S. Pat. No. 6,990,729 B2 to Harris Corp., titled “Method for forming an inductor”, suggests an inductor and a method for forming an inductor. The method includes forming in a ceramic substrate a first plurality of conductive vias radially spaced a first distance from a central axis so as to define an inner circumference. A second plurality of conductive vias is formed radially spaced a second distance about the central axis so as to define an outer circumference. A first plurality of conductive traces forming an electrical connection between substantially adjacent ones of the first and second plurality of conductive vias is formed in a first plane defined orthogonal to said central axis. The conductive vias and the conductive traces together define a three-dimensional toroidal coil. However, it fails to suggest the specific spacing between the adjacent vias is not identical thus, leading to no uniformity in the distance between the adjacent vias hence, a decrease in resonance.
A PCT Application number WO 2010004491 A1 to Rijck Alexander C. De titled, “Toroidal coil arrangement”, discloses a first toroidal coil with a first set of windings which progress in a counterclockwise direction along the toroid, and a second set of toroidal coils with a second set of windings, wherein both toroid coils are electrically connected with each other. The coil arrangement in the PCT application is especially suitable for use as a part of an electronic circuit which is positioned within the examination volume of a magnetic resonance imaging system, because the net axial magnetic field of this coil arrangement is substantially reduced so that disturbing interferences with the functioning of the MM system, especially with the MR image generation, are accordingly decreased or prevented. However, the application fails to address a very important fact of the spacing as well as the distance between the coils, which leads to a lack of uniformity in resonance.